阅读说明：本技术 燃料电池系统 (Fuel cell system ) 是由 小关真弘 石川智隆 西田裕介 于 2021-04-28 设计创作，主要内容包括：本发明涉及一种燃料电池系统。燃料电池系统包括：燃料电池；被构造成获取是燃料电池的温度的第一温度的第一温度传感器；用于操作燃料电池的多个辅助设备；被构造成获取是该多个辅助设备中的至少任一个辅助设备的温度的第二温度的第二温度传感器；和被构造成对该多个辅助设备执行控制以执行燃料电池的预热运行的控制器。控制器被构造成当第一条件和第二条件中的任一个条件得到满足时执行预热运行,其中第一条件是第一温度低于预定的第一阈值温度的条件,并且第二条件是第一温度等于或高于第一阈值温度且第二温度低于预定的第二阈值温度的条件。(The present invention relates to a fuel cell system. The fuel cell system includes: a fuel cell; a first temperature sensor configured to acquire a first temperature that is a temperature of the fuel cell; a plurality of auxiliary devices for operating the fuel cell; a second temperature sensor configured to acquire a second temperature that is a temperature of at least any one of the plurality of auxiliary devices; and a controller configured to perform control of the plurality of auxiliary devices to perform warm-up operation of the fuel cell. The controller is configured to perform the warm-up operation when any one of a first condition and a second condition is satisfied, wherein the first condition is a condition that the first temperature is lower than a predetermined first threshold temperature, and the second condition is a condition that the first temperature is equal to or higher than the first threshold temperature and the second temperature is lower than a predetermined second threshold temperature.)

1. A fuel cell system comprising:

a fuel cell;

a first temperature sensor configured to acquire a first temperature, the first temperature being a temperature of the fuel cell;

a plurality of auxiliary devices for operating the fuel cell;

a second temperature sensor configured to acquire a second temperature that is a temperature of at least any one of the plurality of auxiliary devices; and

a controller configured to perform control of the plurality of auxiliary devices to perform a warm-up operation of the fuel cell,

wherein the controller is configured to execute the warm-up operation when any one of a first condition and a second condition is satisfied, wherein the first condition is a condition that the first temperature is lower than a predetermined first threshold temperature, and the second condition is a condition that the first temperature is equal to or higher than the first threshold temperature and the second temperature is lower than a predetermined second threshold temperature.

2. The fuel cell system according to claim 1, wherein the second temperature is a temperature of an auxiliary device that exhibits a lower temperature than the temperature of the fuel cell in a period in which the fuel cell system is stopped, among the plurality of auxiliary devices.

3. The fuel cell system according to claim 2, wherein:

the plurality of auxiliary devices include an intercooler configured to cool cathode gas supplied to a cathode of the fuel cell; and is

The second temperature is a temperature of the intercooler.

4. The fuel cell system according to any one of claims 1 to 3, wherein the controller is configured to:

when the first condition is satisfied, the warm-up operation is performed after performing control on the plurality of auxiliary devices to perform an anode gas filling process of filling an anode of the fuel cell with an anode gas, and

when the second condition is satisfied, the warm-up operation is performed without performing the anode gas filling process.

5. The fuel cell system according to any one of claims 1 to 4, wherein the controller is configured to: when the temperatures of two or more auxiliary devices among the plurality of auxiliary devices are acquired as the second temperature to perform the warm-up operation, determining whether to end the warm-up operation using the temperatures of the two or more auxiliary devices.

Technical Field

The present disclosure relates to a fuel cell system.

Background

There is known a fuel cell system which performs a warm-up operation of a fuel cell stack until a temperature of a cooling medium at a cooling medium outlet exceeds a preset warm-up end temperature when the temperature of the cooling medium outlet acquired by a temperature sensor provided in a cooling medium circulation system of the fuel cell stack at the time of start is below freezing point (for example, japanese unexamined patent application publication No. 2017-195021 (JP 2017-195021A)).

Disclosure of Invention

Only the temperature of the fuel cell stack is taken into consideration in the warm-up operation of the fuel cell system, and there is room for further improvement from the viewpoint of the starting performance of the entire fuel cell system.

The present disclosure can be implemented as the following aspects.

(1) One aspect of the present disclosure relates to a fuel cell system. The fuel cell system includes a fuel cell, a first temperature sensor, a plurality of auxiliary devices, a second temperature sensor, and a controller. The first temperature sensor is configured to acquire a first temperature that is a temperature of the fuel cell. The plurality of auxiliary devices are used to operate the fuel cell. The second temperature sensor is configured to acquire a second temperature that is a temperature of at least any one of the plurality of auxiliary devices. The controller is configured to perform control over the plurality of auxiliary devices to perform warm-up operation of the fuel cell. The controller is configured to perform a warm-up operation when any one of a first condition and a second condition is satisfied, wherein the first condition is a condition that the first temperature is lower than a predetermined first threshold temperature, and the second condition is a condition that the first temperature is equal to or higher than the first threshold temperature and the second temperature is lower than a predetermined second threshold temperature. With the fuel cell system of this aspect, even if the first temperature, which is the temperature of the fuel cell, is higher than the first threshold temperature, the controller performs the warm-up operation when the second temperature, which is the temperature of the auxiliary, is lower than the second threshold temperature. Even if the temperature of the fuel cell is high to the extent that the warm-up operation is not required, the warm-up operation is performed when the temperature of the auxiliary equipment is low. Therefore, it is possible to reliably suppress or restrain freezing of the auxiliary equipment and improve the starting performance of the entire fuel cell system.

(2) In the fuel cell system according to the aspect, the second temperature may be a temperature of one of the plurality of auxiliary devices that exhibits a temperature lower than a temperature of the fuel cell in a period in which the fuel cell system is stopped. With the fuel cell system of this aspect, the temperature of the auxiliary equipment that exhibits a lower temperature than the temperature of the fuel cell is used for the start condition of the warm-up operation, and freezing of the auxiliary equipment can be suppressed or restrained more reliably.

(3) In the fuel cell system according to the aspect, the plurality of auxiliary devices may include an intercooler configured to cool the cathode gas supplied to the cathode of the fuel cell. The second temperature may be a temperature of the intercooler. With the fuel cell system of this aspect, the temperature of the intercooler, which is likely to be disposed at a position susceptible to the outside air temperature, tends to standardly include the temperature sensor configured to acquire the temperature of the cathode gas, is acquired as the second temperature. Therefore, it is possible to acquire the temperature of the auxiliary equipment exhibiting a low temperature and efficiently determine the need for the warm-up operation without adding a temperature sensor used for the starting condition of the warm-up operation.

(4) In the fuel cell system according to the aspect, the controller may be configured to perform the warm-up operation after performing control on the plurality of auxiliary devices to perform the anode gas filling process of filling the anode of the fuel cell with the anode gas when the first condition is satisfied, and perform the warm-up operation without performing the anode gas filling process when the second condition is satisfied. With the fuel cell system of this aspect, the hydrogen filling process is executed only when the temperature of the fuel cell is low to the extent that the warm-up operation is required, so that unnecessary fuel gas consumption can be suppressed.

(5) In the fuel cell system according to the aspect, the controller may be configured to end the warm-up operation when the temperatures of all of two or more of the plurality of auxiliary devices are equal to or higher than a predetermined end threshold temperature when the temperatures of the two or more auxiliary devices are acquired as the second temperature to perform the warm-up operation. With the fuel cell system of the aspect, the temperatures of the plurality of auxiliary devices are used for the completion condition of the warm-up operation, so that even if the gradient of the temperature rise of each auxiliary device due to the warm-up operation is different, such as when each auxiliary device has a different heat capacity or has a different distance from the fuel cell, it is possible to sufficiently raise the temperature of each auxiliary device and reliably suppress or restrain the freezing of each auxiliary device.

The present disclosure can be implemented in various aspects other than the above-described aspects, and can be implemented, for example, in a vehicle in which a fuel cell system is installed, a control method of the fuel cell system, a method of determining the need for warm-up operation, a computer program for implementing such a method, a storage medium storing such a computer program, and the like.

Drawings

Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like elements, and wherein:

fig. 1 is an explanatory view showing the configuration of a fuel cell system of a first embodiment;

fig. 2 is a flowchart showing a startup process performed by the controller;

fig. 3 is a timing chart showing a part of the startup processing;

fig. 4 is a flowchart showing a startup process performed by the fuel cell system of the second embodiment; and is

Fig. 5 is a timing chart showing a part of the starting process performed by the fuel cell system of the second embodiment.

Detailed Description

A. The first embodiment:

fig. 1 is an explanatory view showing the configuration of a fuel cell system 100 in the embodiment. The fuel cell system 100 is mounted in, for example, a fuel cell vehicle having the fuel cell 20 as a drive source. The fuel cell system 100 uses the generated electric power of the fuel cell 20 to drive various devices included in the load LD. The fuel cell system 100 has a fuel cell 20, a controller 60, an oxidant gas supply and exhaust system 30, a fuel gas supply and exhaust system 50, and a cooling medium circulation system 70. The fuel cell system 100 may further include a secondary battery that serves as an electric power source for the load LD along with the fuel cell 20. The fuel cell system 100 may be used for household power, stationary power generation, and the like, in addition to being used for a fuel cell vehicle.

The fuel cell 20 has a stack structure in which a plurality of unit cells having a Membrane Electrode Assembly (MEA) in which two electrodes of an anode and a cathode are bonded to both sides of an electrolyte membrane are stacked. The fuel cell 20 is a solid polymer fuel cell that generates electric power with the supply of hydrogen gas as a fuel gas and air as an oxidant gas as reaction gases, and drives the load LD using the generated electric power. Examples of the load LD include a drive motor that generates drive power of the fuel cell vehicle and a heater for air conditioning in the fuel cell vehicle. The fuel cell 20 is not limited to the solid polymer type, and may be various types of fuel cells such as a phosphoric acid type, a molten carbonate type, and a solid oxide type.

The controller 60 is constructed of a microcomputer including a microprocessor performing logical operations and a memory such as a ROM or a RAM. The controller 60 executes, by the microprocessor, a program stored in the memory to perform various controls of the fuel cell system 100, including operation controls for a plurality of auxiliary devices used to operate the fuel cell 20. Examples of the "plurality of auxiliary devices" include respective valves included in the oxidant gas supply and discharge system 30, the fuel gas supply and discharge system 50, and the cooling medium circulation system 70, an ejector 54, a gas-liquid separator 57, the air compressor 33, the intercooler 35, the circulation pump 55, and the cooling medium circulation pump 74. Each auxiliary device is thermally coupled to the fuel cell 20, and for example, the temperature of each auxiliary device can be increased as the temperature of the fuel cell 20 increases. The thermal coupling to the fuel cell 20 can be achieved, for example, by being connected to the fuel cell 20 through a component such as a heat pipe or a heat pump or a pipeline in addition to a cooling system such as the cooling medium circulation system 70 that circulates a cooling medium, being provided in the same space as the fuel cell 20, or the like. Note that each valve, the ejector 54, the air compressor 33, the circulation pump 55, and the cooling medium circulation pump 74 may be included in the above-described load LD.

The oxidant gas supply and exhaust system 30 includes: an oxidant gas supply system 30A having a cathode gas supply function; and an oxidant gas exhaust system 30B having a cathode gas exhaust function and a cathode gas bypass function. The cathode gas supply function refers to a function of supplying air including oxygen as a cathode gas to the cathode of the fuel cell 20. The cathode gas discharge function refers to a function of discharging cathode off-gas, which is exhaust gas to be discharged from the cathode of the fuel cell 20, to the outside. The cathode gas bypass function refers to a function of discharging a part of the supplied cathode gas to the outside while restricting the supply to the fuel cell 20.

The oxidant gas supply system 30A supplies air as a cathode gas to the cathode of the fuel cell 20. The oxidant gas supply system 30A has a cathode supply pipe 302, an air cleaner 31, an air compressor 33, an intercooler 35, an IC temperature sensor 38, and an inlet valve 36.

The cathode supply pipe 302 is a pipe connected to an inlet of the cathode of the fuel cell 20, and is a supply flow path of air to the cathode of the fuel cell 20. The air cleaner 31 is provided in the cathode supply pipe 302 on a side closer to the side of the intake port of the air than the air compressor 33 (upstream thereof), that is, upstream of the air compressor 33, and removes foreign matters in the air supplied to the fuel cell 20. An outside air temperature sensor that measures the temperature of outside air may be provided upstream of the air cleaner 31.

An air compressor 33 is provided upstream of the fuel cell 20 in the cathode supply pipe 302. The air compressor 33 compresses air drawn through the air cleaner 31 and pumps the compressed air to the cathode. As the air compressor 33, for example, a turbo compressor is used. The driving of the air compressor 33 is controlled by the controller 60.

An intercooler 35 is provided between the air compressor 33 in the cathode supply pipe 302 and the fuel cell 20. The intercooler 35 cools the cathode gas that is compressed by the air compressor 33 and raised to a high temperature. The cooling method of the cathode gas by the intercooler 35 can be realized, for example, by circulating a cooling medium into the intercooler 35. A line branched from the cooling medium circulation path 79 may be connected to the intercooler 35, and the cooling medium of the cooling medium circulation system 70 may be circulated into the intercooler 35 to cool the cathode gas. The IC temperature sensor 38 acquires the temperature of the intercooler 35. Typically, the intercooler 35 is provided near an introduction port of the outside air. Therefore, the intercooler 35 is likely to be lowered in temperature due to the influence of the outside air temperature, and tends to standardly include the IC temperature sensor 38 to acquire the temperature of the cathode gas to be introduced into the fuel cell 20. In this embodiment, the intercooler 35 displays a temperature lower than the temperature of the fuel cell 20 in the period in which the fuel cell system 100 is stopped, and displays the lowest temperature among the plurality of auxiliary devices of the fuel cell system 100. The description of "an auxiliary device that shows a lower temperature than the temperature of the fuel cell 20 among the plurality of auxiliary devices" refers to an auxiliary device that is thermally coupled to the fuel cell 20 and has a temperature to be obtained that shows a tendency to be lower than the temperature of the fuel cell 20 among the plurality of auxiliary devices whose temperatures can be directly or indirectly obtained by the fuel cell system 100. The description of "the auxiliary device showing the lowest temperature among the plurality of auxiliary devices" refers to the auxiliary device that is thermally coupled to the fuel cell 20 and has a temperature to be obtained showing the lowest tendency among the plurality of auxiliary devices whose temperatures can be directly or indirectly obtained by the fuel cell system 100. The temperature of the auxiliary device is hereinafter also referred to as "second temperature", and the temperature sensor that acquires the temperature of the auxiliary device is hereinafter also referred to as "second temperature sensor". The temperature of the intercooler 35 corresponds to the second temperature, and the IC temperature sensor 38 corresponds to the second temperature sensor. The auxiliary equipment that acquires the second temperature for this purpose may be set in advance, for example, based on the result of the test or the like, or may be appropriately changed based on the temperatures of a plurality of auxiliary equipment acquired by the fuel cell system 100. The temperature of the auxiliary device is not limited to the temperature of the auxiliary device itself, and may be the temperature of the auxiliary device to be indirectly acquired using the temperature in the vicinity of the auxiliary device, or may be an estimated value of the temperature of the auxiliary device calculated using the temperature of a part other than the auxiliary device. For example, the temperature of the intercooler 35 is not limited to the temperature of the intercooler 35 itself, and the temperature of the air flowing through the intercooler 35 or the temperature of the cathode supply pipe 302 near the intercooler 35, or an estimated value of the temperature of the intercooler 35 calculated using such a temperature, may be used. When the temperature of the auxiliary equipment is below, for example, the freezing of the auxiliary equipment or the freezing of liquid water in the auxiliary equipment may affect the start-up of the fuel cell 20. The measurement result of the temperature of the intercooler 35 by the IC temperature sensor 38 is transmitted to the controller 60.

The inlet valve 36 controls the flow of cathode gas into the cathode of the fuel cell 20. The inlet valve 36 is an on-off valve that is mechanically opened when the cathode gas at a predetermined pressure flows.

The oxidant gas exhaust system 30B has a cathode off-gas exhaust function, and includes an exhaust pipe 306 and a bypass pipe 308. The exhaust pipe 306 is an exhaust flow path of the cathode off-gas connected to the outlet of the cathode of the fuel cell 20. The exhaust pipe 306 guides the exhaust gas of the fuel cell 20 including the cathode off-gas into the air. In addition to the cathode exhaust gas, the exhaust gas discharged from the exhaust pipe 306 into the air includes the anode exhaust gas, or the air flowing out from the bypass pipe 308.

The exhaust pipe 306 is provided with an outlet valve 37. The outlet valve 37 is provided on a side closer to the fuel cell 20 than the connection position in the exhaust pipe 306 to the bypass pipe 308. As the outlet valve 37, for example, an electromagnetic valve or an electrically operated valve can be used. The controller 60 adjusts the back pressure of the cathode of the fuel cell 20 by adjusting the opening degree of the outlet valve 37.

The bypass pipe 308 is a line that connects the cathode supply pipe 302 and the exhaust pipe 306 without passing through the fuel cell 20. The bypass pipe 308 is provided with a bypass valve 39. As the bypass valve 39, for example, an electromagnetic valve or an electrically operated valve can be used. When the bypass valve 39 is opened, a part of the cathode gas flowing through the cathode supply pipe 302 flows into the exhaust pipe 306. The controller 60 adjusts the flow rate of the cathode gas flowing into the bypass pipe 308 by adjusting the opening degree of the bypass valve 39.

The fuel gas supply and exhaust system 50 includes a fuel gas supply system 50A having an anode gas supply function, a fuel gas exhaust system 50C having an anode gas exhaust function, and a fuel gas circulation system 50B having an anode gas circulation function. The anode gas supply function refers to a function of supplying an anode gas including a fuel gas to the anode of the fuel cell 20. The anode gas discharge function refers to a function of discharging anode off-gas, which is exhaust gas to be discharged from the anode of the fuel cell 20, to the outside. The anode gas circulation function refers to a function of circulating hydrogen included in the anode off-gas into the fuel cell system 100.

The fuel gas supply system 50A supplies an anode gas including hydrogen to the anode of the fuel cell 20. The fuel gas supply system 50A includes an anode supply pipe 501, a fuel gas tank 51, an on-off valve 52, a regulator 53, and an injector 54.

The anode supply pipe 501 is a line that connects the fuel gas tank 51 as a supply source of hydrogen gas and the inlet of the anode of the fuel cell 20 and supplies the anode gas to the fuel cell 20. The on-off valve 52 is provided in the anode supply pipe 501 near the outlet of the fuel gas tank 51. The on-off valve 52 is also referred to as a main stop valve, and allows the hydrogen gas in the fuel gas tank 51 to flow to the downstream side. The regulator 53 is provided in the anode supply pipe 501 on a side closer to the fuel cell 20 than the on-off valve 52, that is, downstream of the on-off valve 52. The regulator 53 regulates the pressure of the hydrogen gas upstream of the ejector 54 under the control of the controller 60.

The injector 54 is provided downstream of the regulator 53 in the anode supply pipe 501. The injector 54 is an on-off valve controlled by the controller 60, and is electromagnetically driven depending on a set drive cycle or valve open time. The ejector 54 adjusts the amount of hydrogen of the anode gas supplied to the fuel cell 20.

The fuel gas circulation system 50B separates a liquid component from the anode off-gas discharged from the anode of the fuel cell 20, and circulates the anode off-gas into the anode supply pipe 501. The fuel gas circulation system 50B has an anode circulation pipe 502, a gas-liquid separator 57, a circulation pump 55, and a separator temperature sensor 59.

The anode circulation pipe 502 is connected to an anode outlet of the fuel cell 20 and the anode supply pipe 501, and guides anode off-gas discharged from the anode to the anode supply pipe 501. The gas-liquid separator 57 is provided in the anode circulation pipe 502, and separates a liquid component including vapor from the anode off-gas and stores the liquid component. The circulation pump 55 is provided between the gas-liquid separator 57 and the anode supply pipe 501 in the anode circulation pipe 502. The circulation pump 55 pumps the anode off-gas flowing into the gas-liquid separator 57 to the anode supply pipe 501. The separator temperature sensor 59 acquires the temperature of the gas-liquid separator 57 as an auxiliary device. The temperature of the gas-liquid separator 57 corresponds to "the second temperature", and the separator temperature sensor 59 corresponds to "the second temperature sensor". The measurement result of the separator temperature sensor 59 is transmitted to the controller 60. For example, the separator temperature sensor 59 may be attached to the gas-liquid separator 57 to directly acquire the temperature of the gas-liquid separator 57, or may be provided in the anode circulation pipe 502 or the anode drain pipe 504 near the gas-liquid separator 57 to indirectly acquire the temperature of the gas-liquid separator 57 by calculating the temperature of the gas-liquid separator 57 using the temperature of the anode gas or the pipe. When the separator temperature sensor 59 is not used in the startup process described below, the separator temperature sensor 59 may not be provided.

The fuel gas discharge system 50C discharges the anode off-gas or liquid water stored in the gas-liquid separator 57 to the exhaust pipe 306. The fuel gas discharge system 50C has an anode discharge pipe 504 and a gas/water discharge valve 58. The anode discharge pipe 504 is a pipe line that connects the discharge port of the gas-liquid separator 57 and the exhaust pipe 306, and discharges the waste water from the gas-liquid separator 57 and a part of the anode off-gas that passes through the gas-liquid separator 57 from the fuel gas supply and discharge system 50. The gas/water discharge valve 58 is provided in the anode discharge pipe 504, and opens and closes a flow path of the anode discharge pipe 504. As the gas/water discharge valve 58, for example, a diaphragm valve can be used. When the gas/water discharge valve 58 is opened, the liquid water and the anode off-gas stored in the gas-liquid separator 57 are discharged into the air through the gas discharge pipe 306.

The cooling medium circulation system 70 circulates a cooling medium into the fuel cell 20 to regulate the temperature of the fuel cell 20. As the cooling medium, for example, a non-freezing fluid such as ethylene glycol, water, or the like is used. The cooling medium circulation system 70 includes a cooling medium circulation path 79, a cooling medium circulation pump 74, a radiator 71, a radiator fan 72, and a fuel cell temperature sensor 73.

The cooling medium circulation path 79 has a cooling medium supply path 79A that supplies the cooling medium to the fuel cell 20 and a cooling medium discharge path 79B that discharges the cooling medium from the fuel cell 20. The cooling medium circulation pump 74 pumps the cooling medium of the cooling medium supply path 79A to the fuel cell 20. The radiator 71 radiates heat by wind from a radiator fan 72 and cools the cooling medium flowing therethrough.

The fuel cell temperature sensor 73 acquires the temperature of the fuel cell 20. The temperature of the fuel cell 20 is not limited to the temperature of the fuel cell 20 itself, and includes the temperature of an auxiliary line in the vicinity of the fuel cell 20, or includes an estimated value, such as a calculated value, of the temperature of the fuel cell 20. In this embodiment, the fuel cell temperature sensor 73 acquires the temperature of the cooling medium in the cooling medium discharge path 79B as the temperature of the fuel cell 20. The temperature of the fuel cell 20 is also referred to as "first temperature", and the fuel cell temperature sensor 73 that acquires the temperature of the fuel cell 20 is also referred to as "first temperature sensor". The measurement result of the fuel cell temperature sensor 73 is transmitted to the controller 60.

Fig. 2 is a flowchart showing the startup process executed by the controller 60. For example, when the start of the operation of the fuel cell system 100 is instructed by an activating operation (such as pressing a start switch of the fuel cell vehicle), the start-up process is executed by the controller 60. With the start of the startup process, the controller 60 operates the fuel cell 20 to start power generation. More specifically, the controller 60 performs control of the respective auxiliaries of the oxidant gas supply-exhaust system 30 and the fuel gas supply-exhaust system 50 to start supply of the reaction gas to the fuel cell 20 and discharge of the reaction gas from the fuel cell 20, and performs control of the respective auxiliaries of the cooling medium circulation system 70 to start temperature control of the fuel cell 20.

The controller 60 acquires the temperature of the fuel cell 20 as the first temperature Tl (step S10). The controller 60 acquires the temperature of the cooling medium in the cooling medium discharge path 79B acquired by the fuel cell temperature sensor 73 as the first temperature T1. The controller 60 uses the acquired first temperature T1 to determine whether the first condition, which is the starting condition of the warm-up operation, is satisfied (step S12). In this embodiment, the controller 60 determines that the first condition is satisfied when the measured value of the fuel cell temperature sensor 73 is lower than a predetermined temperature (hereinafter, also referred to as "first threshold temperature TA") that is a temperature required for the warm-up operation. In this embodiment, the first threshold temperature TA is set to freezing point. The first threshold temperature TA may be optionally set using a temperature sufficient to normally start the fuel cell 20, or a temperature of each auxiliary device used when operating the fuel cell 20. Preferably, the first threshold temperature TA is, for example, close to freezing point. When the fuel cell 20 can be normally started even at a temperature below the freezing point, the first threshold temperature TA may be set to a temperature below the freezing point. The first threshold temperature TA may be set to a temperature higher than the freezing point.

When it is determined that the first condition is satisfied (S12: YES), the controller 60 performs a hydrogen filling process (step S13). The "hydrogen filling process" is a process of introducing hydrogen into the anode to fill the anode with hydrogen sufficient for the power generation of the fuel cell 20 while discharging a mixed gas including impurities present in the anode. The hydrogen filling process is also referred to as an "anode gas filling process" or a "hydrogen replacement process". For example, when the temperature of the fuel cell 20 is low to the extent that the warm-up operation is required, the flow path of the fuel gas, such as the anode supply pipe 501 or the anode circulation pipe 502, is frozen and the circulation of the fuel gas is likely to be hindered. For this reason, the hydrogen filling process is preferably performed in a low-temperature environment, and more preferably in an environment in which the temperature of the fuel cell 20 is low to such an extent that the warm-up operation is required. The controller 60 performs control of the on-off valve 52, the injector 54, and the like to supply hydrogen gas to the anode, while opening the gas/water discharge valve 58 to discharge the mixed gas from the anode. The controller 60 closes the gas/water discharge valve 58 to complete the hydrogen filling process. The hydrogen filling process may be omitted when the fuel gas can be sufficiently supplied to the fuel cell 20, such as when the temperature of the fuel cell 20 is higher than, for example, the freezing point.

In the case where the hydrogen filling process is completed, the controller 60 performs the warm-up operation (step S14). More specifically, the controller 60 performs control of the oxidant gas supply and exhaust system 30 and the fuel gas supply and exhaust system 50 such that the stoichiometric ratio of the oxidant gas supplied to the fuel cell 20 is smaller than that during normal operation. "stoichiometric ratio of the oxidant gas" refers to a ratio of an actual supply amount of the oxidant gas to a theoretical value of an amount of the oxidant gas required to generate required generated electric power. By this control, since the concentration overvoltage in the cathode increases and the power generation efficiency of the fuel cell 20 deteriorates, the heat generation amount of the fuel cell 20 increases and the temperature increase speed of the fuel cell 20 can be increased as compared with the normal operation. The stoichiometric ratio of the oxidant gas during the warm-up operation can be set to, for example, about 1.0. The controller 60 controls the current of the fuel cell 20 to cause the fuel cell 20 to generate electric power at the target heat generation amount while supplying the reaction gas to the fuel cell 20 at the stoichiometric ratio for the warm-up operation. When the current outside air temperature or the first and second temperatures are low, the controller 60 may set the target heat generation amount to a large value.

The controller 60 acquires the first temperature Tl (step S16), and determines whether a predetermined warm-up completion condition is satisfied (step S18). More specifically, when the first temperature T1 is equal to or higher than the predetermined first end threshold temperature TAe, the controller 60 determines that the warm-up completion condition is satisfied. It is preferable that the first end threshold temperature TAe be set to a temperature to such an extent that the startability of the fuel cell 20 is not deteriorated, for example, to a temperature equal to or higher than freezing point. The first end threshold temperature TAe may be set, for example, to the same temperature as the first threshold temperature TA or may be set to a temperature higher than the first threshold temperature TA. For example, the warm-up completion condition may be satisfied when the warm-up completion time calculated from the target heat generation amount has elapsed.

When it is determined that the first temperature T1 is equal to or higher than the first end threshold temperature TAe (S18: yes), the controller 60 completes the warm-up operation to end the starting process and starts the normal operation of the fuel cell 20. When the warm-up completion condition is not satisfied (S18: no), the controller 60 returns to step S14 and continues the warm-up operation until the warm-up completion condition is satisfied.

In step S12, when the first condition is not satisfied (S12: no), the controller 60 acquires a second temperature T2 (step S20). In this embodiment, the controller 60 acquires the temperature of the intercooler 35 as the temperature of the auxiliary device showing the lowest temperature among the plurality of auxiliary devices in the fuel cell system 100 as the second temperature T2. For example, when an auxiliary device other than the intercooler 35 among the plurality of auxiliary devices in the fuel cell system 100 shows the lowest temperature, the temperature of the auxiliary device may be used as the second temperature T2.

The controller 60 determines whether the second condition, which is a start condition of the warm-up operation, is satisfied using the second temperature T2 (step S22). In this embodiment, when the measurement value of the IC temperature sensor 38 is lower than a predetermined temperature (hereinafter, also referred to as "second threshold temperature TB"), the controller 60 determines that the second condition is satisfied. As with the first threshold temperature TA, the second threshold temperature TB is set to the freezing point. It is preferable that the second threshold temperature TB be set to any temperature sufficient to normally start each auxiliary device for use in operating the fuel cell 20. The second threshold temperature TB may be set to a temperature lower than the first threshold temperature TA or freezing point or may be set to a temperature higher than the first threshold temperature TA or freezing point depending on the starting performance of each auxiliary.

When it is determined that the second condition is satisfied (S22: YES), the controller 60 performs a warm-up operation (step S24). The warm-up operation of step S24 may be performed under the same conditions as the warm-up operation of step S14, or may be performed under different conditions from step S14. As the warm-up operation under different conditions, for example, various warm-up operations can be employed, such as a warm-up operation in which the amount of heat generation during rapid warm-up is different, and a warm-up operation in which the circulation amount of the cooling medium or the circulation path of the cooling medium is different. The warm-up operation to be performed can be decided under various conditions such as the characteristics of the auxiliary devices, the distance or setting relationship between the fuel cell 20 and the auxiliary devices, and the state of thermal coupling to the fuel cell 20. For example, the target heat generation amount of the fuel cell 20 may be set to a target value different from step S14 based on the heat capacity of the auxiliary as the characteristic of the auxiliary. When the second condition is not satisfied (S22: no), the controller 60 ends the flow and starts the normal operation without performing the warm-up operation.

When the given time has elapsed from the start of the warm-up operation, the controller 60 acquires the second temperature T2 (step S26), and determines whether a predetermined warm-up completion condition is satisfied (step S28). More specifically, when the second temperature T2 is equal to or higher than a predetermined second end threshold temperature TBe, the controller 60 determines that the warm-up completion condition is satisfied. It is preferable that the second end threshold temperature TBe be set to a temperature to the extent that the startability of each auxiliary in the fuel cell system 100 is not deteriorated, for example, to a temperature equal to or higher than freezing point. For example, the second end threshold temperature TBe may be set to the same temperature as the second threshold temperature TB or the first end threshold temperature TAe, or may be set to a temperature higher than the second threshold temperature TB or the first end threshold temperature TAe. For example, the warm-up completion condition may be satisfied when the warm-up completion time calculated from the target heat generation amount has elapsed. When it is determined that the second temperature T2 is equal to or higher than the second end threshold temperature TBe (S28: yes), the controller 60 completes the warm-up operation to end the flow and starts the normal operation of the fuel cell 20. When the warm-up completion condition is not satisfied (S28: no), the controller 60 returns to step S24 and continues the warm-up operation until the warm-up completion condition is satisfied.

Fig. 3 is a timing chart showing a part of the startup processing executed by the controller 60. In fig. 3, the temperature of the fuel cell 20 as the first temperature Tl, the temperature of the intercooler 35 as the second temperature T2, and the on-off control of the warm-up operation performed by the controller 60 are shown in this order from the uppermost layer. The horizontal axis is the time axis, and the time axis of each item is uniform. Time TM0 shown in fig. 3 represents the start time of the startup processing. In the period from the time TM0 to the time TM1, the first temperature T1 is a temperature T1s higher than the first threshold temperature TA, and the second temperature T2 is a temperature T2s lower than the second threshold temperature TB.

The controller 60 starts power generation of the fuel cell 20 with the start of the startup process, and acquires the first temperature T1 at time TM 1. The first temperature T1 is a temperature T1s that is higher than the first threshold temperature TA, and the first condition is not satisfied. To do so, the controller 60 obtains the second temperature T2 and determines whether the second condition is satisfied. The second temperature T2 is a temperature T2s lower than the second threshold temperature TB, and the second condition is satisfied. Accordingly, the controller 60 starts the warm-up operation. With the start of the warm-up operation, after TM1, the temperature of the fuel cell 20 rises. The temperature of the intercooler 35 increases due to heat transfer from the fuel cell 20, and reaches the second end threshold temperature TBe at TM 2. The controller 60 determines that the warm-up completion condition is satisfied and completes the warm-up operation.

As described above, with the fuel cell system 100 of this embodiment, even if the first temperature T1, which is the temperature of the fuel cell 20, is higher than the first threshold temperature TA, the controller 60 performs the warm-up operation when the second temperature T2, which is the temperature of the auxiliary, is lower than the second threshold temperature TB. Even if the temperature of the fuel cell 20 is high to the extent that the warm-up operation is not required, the warm-up operation is performed when it is determined that the temperature of the auxiliary equipment is low to the extent that the warm-up operation is required. Therefore, it is possible to reliably suppress or restrain freezing of the auxiliary equipment and improve the starting performance of the entire fuel cell system 100.

With the fuel cell system 100 of this embodiment, the controller 60 acquires, as the second temperature T2, the temperature of the auxiliary that exhibits a temperature lower than the temperature of the fuel cell 20 in the period in which the fuel cell system 100 is stopped. The temperature of the auxiliary equipment, which exhibits a temperature lower than that of the fuel cell 20, is used for the start condition of the warm-up operation, whereby freezing of the auxiliary equipment can be suppressed or restrained more reliably.

With the fuel cell system 100 of this embodiment, the controller 60 acquires, as the second temperature T2, the temperature of one of the auxiliary devices that exhibits the lowest temperature during the period in which the fuel cell system 100 is stopped. Therefore, the need for the warm-up operation can be effectively determined without using the temperature of the other auxiliary equipment for the start condition of the warm-up operation.

With the fuel cell system 100 of this embodiment, the temperature of the intercooler 35 is used as the second temperature T2. In general, the intercooler 35 is likely to be disposed at a position susceptible to the outside air temperature, and tends to standardly include an IC temperature sensor 38 to acquire the temperature of the cathode gas. Therefore, it is possible to acquire the temperature of the auxiliary equipment exhibiting a low temperature and efficiently determine the need for the warm-up operation without adding a temperature sensor used for the starting condition of the warm-up operation.

With the fuel cell system 100 of this embodiment, the controller 60 performs the warm-up operation after performing the hydrogen filling process when the first condition is satisfied, and performs the warm-up operation without performing the hydrogen filling process when the second condition is satisfied. The hydrogen filling process is executed only when the temperature of the fuel cell 20 is low to the extent that the warm-up operation is required, so that wasteful consumption of the fuel gas can be suppressed.

B. Second embodiment:

fig. 4 is a flowchart showing a start-up process performed by the fuel cell system 100 of the second embodiment of the present disclosure. In the fuel cell system 100 of the second embodiment, a part of the starting process performed by the controller 60 is different from that of the first embodiment. More specifically, the start-up processing performed by the fuel cell system 100 of this embodiment includes steps S30 through S38 instead of the steps S20 through S28 shown as the first embodiment. The other configurations of the fuel cell system 100 are the same as those in the first embodiment.

As in the first embodiment, the controller 60 acquires the temperature of the fuel cell 20 as the first temperature Tl (step S10), and determines whether the first condition is satisfied (step S12). When the first condition is not satisfied (S12: no), the controller 60 acquires the temperature of the intercooler 35 as the second temperature T21, and the temperature of the gas-liquid separator 57 as the second temperature T22 (step S30). That is, in this embodiment, the controller 60 acquires the temperatures of two or more auxiliary devices as the second temperature. The controller 60 determines whether the second condition is satisfied using the acquired second temperatures T21, T22 (step S32). In this embodiment, the second threshold temperature is set to a second threshold temperature TB1 corresponding to the second temperature T21, and a second threshold temperature TB2 corresponding to the second temperature T22. When at least either one of the condition that the acquired second temperature T21 is lower than the second threshold temperature TB1 or the condition that the second temperature T22 is lower than the second threshold temperature TB2 is satisfied, the controller 60 determines that the second condition is satisfied. When the temperatures of the plurality of auxiliary devices are not required to determine the start condition of the warm-up operation, only the temperature of one of the plurality of auxiliary devices, such as any one of the temperature of the intercooler 35 and the temperature of the gas-liquid separator 57, may be used in steps S30 and S32.

When it is determined that the second condition is satisfied (S32: YES), the controller 60 performs the warm-up operation under the same conditions as in step S14 or step S24 (step S34). When the second condition is not satisfied (S32: no), the controller 60 ends the flow and starts the normal operation without performing the warm-up operation.

In the case where a given time has elapsed from the start of the warm-up operation, the controller 60 acquires the second temperatures T21, T22 (step S36), and determines whether the warm-up completion condition is satisfied (step S38). In this embodiment, the controller 60 determines that the warm-up completion condition is satisfied when the temperature of all of the two or more auxiliary devices exceeds a predetermined second end threshold temperature. More specifically, the second end threshold temperature is set to a second end threshold temperature TBe1 corresponding to the second temperature T21, and a second end threshold temperature TBe2 corresponding to the second temperature T22. When the second temperature T21 is higher than the second ending threshold temperature TBe1 and the second temperature T22 is higher than the second ending threshold temperature TBe2, the controller 60 determines that the warm-up completion condition is satisfied. The second end threshold temperature TBe1 and the second end threshold temperature TBe2 may be set to different temperatures based on various conditions such as the heat capacity of the auxiliary devices, the distance or setting relationship between each auxiliary device and the fuel cell 20, and the state of thermal coupling to the fuel cell 20, or may be set to the same temperature. When it is determined that the warm-up completion condition is satisfied (S38: yes), the controller 60 completes the warm-up operation to end the flow and start the normal operation of the fuel cell 20. When the warm-up completion condition is not satisfied (S38: no), the controller 60 returns to step S34 and continues the warm-up operation until the warm-up completion condition is satisfied.

Fig. 5 is a timing chart showing a part of the starting process performed by the fuel cell system 100 as the second embodiment. In fig. 5, the temperature of the fuel cell 20 as the first temperature T1, the temperature of the intercooler 35 as the second temperature T21, the temperature of the gas-liquid separator 57 as the second temperature T22, and the on-off control of the warm-up operation performed by the controller 60 are shown in this order from the uppermost layer. In a period from time TM0, which is the starting time of the starting process, to time TM1, the second temperature T21 is a temperature T21s lower than the second threshold temperature TB1, and the second temperature T22 is a temperature T22s higher than the second threshold temperature TB 2.

At time TM1, when the second temperature T22 is equal to or higher than the second threshold temperature TB2, the second temperature T21 is lower than the second threshold temperature TB 1. To this end, the controller 60 determines that the second condition is satisfied and starts the warm-up operation. As the temperature of the fuel cell 20 increases with the start of the warm-up operation, the temperatures of the intercooler 35 and the gas-liquid separator 57 increase with the heat transfer from the fuel cell 20. At time TM3, the second temperature T21 is equal to or higher than the second end threshold temperature TBe1, and the second temperature T22 reaches the second end threshold temperature TBe 2. Accordingly, the controller 60 determines that the warm-up completion condition is satisfied and ends the warm-up operation.

With the fuel cell system 100 of this embodiment, the controller 60 acquires the temperatures of two or more auxiliary devices as the second temperatures T21, T22, and ends the warm-up operation when the temperature of each auxiliary device is equal to or higher than a predetermined second end threshold temperature TBe1 or TBe 2. The temperatures of the plurality of auxiliary devices are used for the completion condition of the warm-up operation, so that even if the gradient of the temperature rise of each auxiliary device due to the warm-up operation is different, such as when each auxiliary device has a different heat capacity or has a different distance from the fuel cell 20, it is possible to sufficiently raise the temperature of each auxiliary device and reliably suppress or restrain the freezing of each auxiliary device.

C. Other examples are as follows:

(C1) in the first embodiment described above, as for the start condition of the warm-up operation, the temperature of the intercooler 35, which is the auxiliary equipment that shows the lowest temperature in the stop period of the fuel cell system 100 among the plurality of auxiliary equipment, is used as the second temperature T2. In contrast, the temperature of the auxiliary other than the auxiliary that shows a temperature lower than the temperature of the fuel cell 20 in the stop period of the fuel cell system 100 (such as the temperature of the auxiliary having the largest heat capacity among the plurality of auxiliaries in the fuel cell system 100 as the second temperature) may be used as the second temperature, and the temperature of the auxiliary other than the auxiliary that shows the lowest temperature may be used as the second temperature. With the fuel cell system 100 of this embodiment, the start condition and the finish condition of the warm-up operation are determined based on the auxiliary devices whose temperatures hardly increase with the warm-up operation, so that it is possible to sufficiently increase the temperature of each auxiliary device at the time of completion of the warm-up operation, and to more reliably suppress or restrain freezing of the auxiliary devices.

(C2) In the second embodiment described above, the controller 60 determines that the warm-up completion condition is satisfied when the temperature of all of the two or more auxiliary devices exceeds the predetermined second end threshold temperature. In contrast, for example, when acquiring the temperatures of two or more auxiliary devices among the plurality of auxiliary devices to perform the warm-up operation, the controller 60 may use the acquired temperatures of the two or more auxiliary devices in any combination to determine whether the warm-up completion condition is satisfied. As this combination, the following combinations 1) to 4) can be employed.

1) The temperature of any one of the auxiliary devices (such as the one that exhibits the lowest temperature);

2) the preset temperatures of a plurality of optional auxiliary devices;

3) the temperature of all auxiliary equipment;

4) and obtaining an average value of the temperatures of the plurality of auxiliary devices.

(C3) In the above-described respective embodiments, a part or all of the functions and processes realized by software may be realized by hardware. Further, part or all of the functions and processes realized by hardware may be realized by software. As hardware, for example, various circuits such as an integrated circuit, a discrete circuit, and a circuit module formed by combining these circuits can be used.

The present disclosure is not limited to the above-described embodiments, and can be implemented by various configurations without departing from the scope of the present disclosure. For example, technical features of the embodiments corresponding to technical features in the aspects described in the summary of the invention may be appropriately replaced or combined to solve a part or all of the above-described problems or to achieve a part or all of the above-described effects. Further, unless technical features are described as necessary in the specification, the technical features may be appropriately deleted.